1. Field of the Disclosure
Exemplary embodiments of the present disclosure relate to an image forming apparatus, and more specifically to a liquid-ejection head unit and an image forming apparatus including the liquid-ejection head unit.
2. Description of the Background
Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, or multi-functional peripherals having two or more of the foregoing capabilities. As one type of image forming apparatus employing a liquid-ejection recording method, an inkjet recording apparatus is known that uses a recording head formed with a liquid ejection head (liquid-droplet ejection head) for ejecting droplets of ink.
Such image forming apparatuses employing the liquid-ejection recording method eject droplets of ink or other liquid from the recording head onto a recording medium to form a desired image (hereinafter “image formation” is used as a synonym for “image recording” and “image printing”). Such liquid-ejection-type image forming apparatuses fall into two main types: a serial-type image forming apparatus that forms an image by ejecting droplets from the recording head while moving the recording head in a main scan direction, and a line-head-type image forming apparatus that forms an image by ejecting droplets from a linear-shaped recording head held stationary in the image forming apparatus.
In such an image forming apparatus employing a liquid ejection head, mist arises in ejecting liquid droplets. Such mist may adhere to an electric-circuit board on which electronic components for driving the head are mounted, causing malfunction or failure of the electric components.
Hence, for example, in a conventional technique described in JP-2003-025562-A, an ink ejection head is proposed that includes a head to eject ink droplets, a head case that holds the head and supplies ink to the head, a cartridge case that supplies ink to the head case, and a circuit board that transmits electric signals to the head. The circuit board is sandwiched between the head case and the cartridge case, and ribs are provided to restrict the movement of the electric board.
In another conventional technique described in JP-2009-000978-A, the head unit is covered with a head spacer member, and an opening of the head spacer member hermetically sealed, with the electric-circuit board connected to the head unit. One side of the electric-circuit board is insulated.
In still another conventional technique described in JP-H10-058756-A, a compact printing device includes a printing unit, an ink storage unit to supply ink to the printing unit, and an electric board to apply electric signals to the printing unit. At least one portion of the surface of the electric circuit is covered with insulation, and the portion covered is disposed inside the ink storage unit.
There is a demand for downsizing such liquid-ejection head units, and components of the head units are increasingly downsized and packaged with higher density. Further, the electric-circuit board that transmits signals to drive the head is increasingly packaged with higher density, and wiring patterns and electronic components are densely deployed. The electronic components and other components may be mounted on both sides of the electric-circuit board, and in consideration of such arrangement, surrounding members need to be separated therefrom. However, as described above, ink mist caused by ink ejection may adhere to and damage the electronic components.
In such a case, for the technique described in JP-2003-025562-A, the electric circuit is not fixed on the cartridge case, gaps remain between the components, thus making it difficult to prevent mist from damaging the electric circuit. For the technique described in JP-2009-000978-A, one side of the electric-circuit board is subjected to insulation processing, causing an increased cost. Further, when the components are disposed on both sides of the board, insulation processing is difficult to perform and upsizing of the head spacer member is needed to contain the head, causing upsizing of an apparatus employing the head unit.
For the technique described in JP-H10-058756-A, a portion of an ink channel is sealed with the insulated electric-circuit board. With such a configuration, jointing of the components is difficult to perform, and since all components implemented on one side of the board need be subjected to insulation processing, it may be difficult to test or evaluate the insulation processing.